48 PROC. ENT. SOC. WASH., VOL. 20, NO. 3, MAR., 1918 



nellum, for regions which, however, do not correspond to the 

 subdivisions here recognized. Thus, in his figure 32 of the meso- 

 sternum of Byrsotria, the sclerite which he designates as the 

 " presternum " is the anterior margin of the basisternum (marked 

 off by an impressed line having no especial phylogenetic signifi- 

 cance), while the socalled "sternum" is largely the posterior 

 portion of the basisternum, and the plate which he terms the 

 "sternellum" is the spinasternum (in which usage he agrees 

 with Voss, 1904). Snodgrass' other applications of the term 

 presternum are quite different from that given in the above- 

 cited figure, and do not correspond to that adopted in the present 

 paper. Thus, in his figures 94, etc., he includes in the term 

 "presternum," the lateral wings of the basisternal region, here 

 termed the laterosternites (fig. 13, fig. 14, fig. 15, etc., Is}. This 

 region has nothing whatsoever to do with the presternum, which 

 is an anterior sternite, not a lateral wing of the basisternal region ; 

 so that it is difficult to understand why he includes the lateral 

 region Is of figures 13, 15, etc., under the designation "presternum." 

 Snodgrass, however, does not apply the term presternum to the 

 same sclerites in every case, for, while he applies the term pre- 

 sternum to the region on either side of the sternum in his figures 

 10, 11, etc., he applies the term pre-episternum to the same 

 region in his figures 29, 46, etc. In his figure 93 of the neck 

 region of Spongiphora, he calls the lateral cervicals the "prester- 

 num," while in his figure 98, he applies the term presternum to 

 yet another plate, so that it is impossible to tell exactly to what 

 region he intends to refer in using the designation presternum, 

 since he applies it to so many different sclerites. The term ster- 

 nellum, however, he uses in but a single instance, and applies 

 it to the spinasternum in this case. 



The terms presternum, basisternum, furcasternum and spina- 

 sternum applied to the four principal sternites here recognized, 

 have been taken over from a paper written nine years ago (Cramp- 

 ton, 1908) at a time when I was not familiar with a large range of 

 insects, but, since certain fixed landmarks were employed to 

 identify these sternal plates, a further study of a wider series of 

 forms has merely confirmed the conclusions concerning the sternal 

 plates set forth in the original paper; and it is only by taking 

 these landmarks into consideration that one can homologize the 

 plates. with any degree of certainty. As was pointed out in the 

 original article, the term "sternum" could not be at the same 

 time time applied to both the entire sternum and also to one of 

 the sternal subdivisions, without creating confusion, and that 

 whatever terminology was accepted, the term basisternum 

 (applied to the basal portion of the sternal region, bs, whose 



